In the continuous print production of such printing presses, the web is, or usually a plurality of webs are printed on with at least two prints arranged next to each other. Viewed in the direction of conveying, the web can be printed on one after another with the same print or in a periodic sequence of two or, in principle, also even more different prints. The web is or the plurality of webs are cut lengthwise between the prints arranged next to each other. A plurality of web strands are converged into a bundle corresponding to the running print production and cut crosswise together at right angles to the direction of conveying of the particular bundle in order to obtain the individual printed products, e.g., newspapers or magazines. In general, a plurality of bundles are converged and cut crosswise together in newspaper printing to obtain the printed product. The web strands, which form a bundle each, are converged such that the prints of the web strands of one bundle are centered as accurately as possible between two consecutive cuts following each other in the direction of conveying. The web strands of one bundle are influenced by means of suitable operations to obtain their so-called crop mark, i.e., for centering between the cuts. Relative to the individual web strand, these operations are changes made specifically on the crop mark of the web strand in question in the path length traveled by the web strand between the site of printing and the site of cross cutting. Thus, the position of the crop mark of the strand in question or, briefly, the crop mark of that strand is set by specifically changing the path length.
Crop mark rollers have proved successful for setting the crop mark. The crop mark rollers are wrapped around by a web strand each, usually over 180°. The path of the web strand wrapping around the crop mark roller is lengthened or shortened by an adjusting movement of a crop mark roller at right angles to its longitudinal axis, and the crop mark of the web strand in question is thus set.
Two or three web strands, which are then converged and folded lengthwise, are usually obtained from the web strand by the lengthwise cutting. To make possible the convergence, the web strands are subjected each individually to one or more suitable turning operations. One of the web strands of the web or, in the case of a plurality of printed webs, one web strand from each web, is not subjected to any turning operation, and is delivered in this sense directly to the site of convergence. Such a web strand will hereinafter be called a direct strand. A web strand that is subjected to one or more turning operations will hereinafter be called a turned strand for distinction.
The present invention also pertains especially to printing presses and web guiding processes of the above-described type.
When the crop mark position of the direct strand of a web strand bundle is set in the prior-art printing presses and web-guiding processes for the direct strand of a web strand bundle, these are settings in the running print production for correcting a deviation of the color mark from the cut. The crop mark position is set anew for each turned strand of the bundle by adjusting the web length of the turned strand in question at the beginning of a new print production, or it is set during the running print production in adaptation to changes in the position of the direct strand. The setting of the crop mark position of the direct strand is not affected hereby. The direct strand forms quasi the leading strand, to which all other web strands of the bundle are set.
One problem is the setting of the press to a new print production. The setting is necessary at the time of the start-up of the press or also at the time of a change in the print production with the press running. The number of copies printed with the same press setting tend to decrease, whereas the number of start-up operations and especially the flying change of the print production with the press running increase to the same extent, i.e., the requirements imposed on the flexibility of the press increase. However, it is increasingly important at the same time to reduce spoilage because of the increasing cost pressure.